The oscillator-amplifier configuration is a known alternative to the plain oscillator in the design of laser sources. In general, it is neither as efficient nor as straightforward as the plain oscillator configuration. It can however, offer a significant advantage where a low power laser source already exists; or where a low power oscillator offers desirable features of quality or control not easily obtainable within a high power oscillator.
A particular problem that arises with such systems is that with high enough overall gain, the amplifier can exhibit super-radiance i.e. can generate output power when no input signal is present. This power can be a significant fraction of the amplifier's maximum output. Furthermore, it will emerge from both the input and output ends of the amplifier. It is therefore essential that super-radiance should be controlled or removed in a practical high power amplifier.